Natural energy (自然エネルギー, Shizen enerugī), is energy that can be collected from the atmosphere and terrain. If one can collect the natural energy from around them and combine and balance it with the spiritual and physical energy that makes up their chakra, they can become sages and enter the Sage Mode, allowing them to use senjutsu. This method can be taught by the inhabitants in one of two legendary locations:

The people of Jūgo's clan have special bodies that are capable of drawing in natural energy. However, as they are unable to control the flux of power that comes with this, they are prone to randomly going berserk. Orochimaru also figured out how to utilise natural energy thanks to Jūgo's abilities and his discovery of the Ryūchi Cave, but was also unable to use it properly because he did not possess strong enough host bodies to use such power.[1]